The present invention relates to a lead frame for packaging a semiconductor die, and more particularly, to a lead frame and method for assembling a semiconductor device with a high count of external connector pads.
One typical type of semiconductor chip package is a Quad Flat Pack (QFP) that is assembled with a semiconductor die mounted to a lead-frame. The lead-frame is formed from a sheet of metal that has a die attach pad often called a flag and tie bars that attach the flag to an outer frame. External connector pads on the lead frame, sometimes referred to as lead fingers, are wire bonded to pads or electrodes of the die to provide a means of electrically connecting the die to circuit boards and the like. After the electrodes and external connector pads are wire bonded, the semiconductor die and external connector pads are encapsulated in a mold compound such as a plastics material to form a semiconductor chip package generally leaving only the outer frame and the undersides of the external connector pads exposed. The semiconductor chip package is then cut from the outer frame (singulated).
Unfortunately, the inherent structure of lead frames for Flat Pack and QFP packages limits the number of external connector pads that can be used for a specific package size. Such a limitation may be in conflict with the general trend in semiconductor technology of doubling the functional complexity of semiconductor chips around every eighteen months. It would therefore be beneficial if lead frames and semiconductor chip packages could provide for increased external connector pad counts.